Yes, Paulo, this is true, these flower motives are made with this technique.
But it can be done with this kind of tool (the simplest, but the one that requires the highest level of skill), or
it can be done with the hammer and chisel / burin ,this method is said to be the easiest for the beginner (that's what I want to practice first)
Then, experts all advice to switch to the pneumatic or electricity driven hand graver like the one your show above.
They say it has both advantages, the single handed work and curve control, and the security of the hammered technique, meaning you never have to push hard with your hand, thus avoiding any risk of big scratch across your 10 hours effort work !
(that's the drawback of the first technique).
I will see, maybe, one day, if I figure out how they are made, I will try to make myself a pneumatic version.
But I need the vice first, and a lot of practice !!
Thanks for the pictures !